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The dinosaur was the size of a turkey and had a neck like a swan, teeth like a crocodile, forelimbs similar to a penguin's flippers, and clawed feet ideal for use on land. It's such a strange assortment of features that researchers who identified the new species from a fossil used X-rays to make sure the nearly complete skeleton wasn't a jumble of unrelated bones. "It looked like an alien," Vincent Fernandez, co-author of a new Nature study, tells the New York Times. "It's like a mixture of things that could have been put together." That was a legitimate concern, as the 75-million-year-old fossil found in southern Mongolia was sold on the black market before an international team of researchers got their hands on it. They say the fossil is indeed real and identify the creature as Halszkaraptor escuilliei, a relative of the velociraptor and perhaps only the second swimming dinosaur ever found.

Researchers explain H. escuilliei's snout, similar to that of a goose, had sensory nerves like those crocodiles use to detect movement in water. The dinosaur's hooked teeth and long neck also would've helped it snatch fish from the surface of lakes and rivers it navigated with flipper-like forelimbs. The long digits of its non-webbed feet may have helped it swim, too, though researchers say the dinosaur likely would've laid its eggs on land, per National Geographic. The fossil—explore a virtual 3D image at Live Science—is now in Belgium but will be returned to Mongolia. For researchers, it represents all of the surprising dinosaur discoveries still to be made. Says study co-author Philip Currie, "Even in very well-known sites, we can still find new animals and show that they have an incredible diversity of forms that we never even expected before." (This equally old fossil held another surprise.)